Charles Spurgeon Commentary 1 John 5:9-10

"If we receive the witness of men, the witness of God is greater: for the witness of God is this, that he hath borne witness concerning his Son. He that believeth on the Son of God hath the witness in him: he that believeth not God hath made him a liar; because he hath not believed in the witness that God hath borne concerning his Son." — 1 John 5:9-10 (ASV)

If we receive the witness of men, the witness of God is greater: for this is the witness of God which he hath testified of his Son. He that believeth on the Son of God hath the witness in himself:

What better witness than this could he have?